Various electronic devices are equipped with display modules of various sizes and shapes and provide a variety of contents through a screen more naturally and dynamically thanks to the development of display technologies.
Since a miniaturization display technique had been applied to an electronic device, a minor substandard state may cause a critical defect. For example, in a conventional electronic device, a minor substandard state which is not detected in the manufacturing process causes a partial damage or malfunction. Such a situation adversely affects the reliability of product.